1. Field of the Invention
The present invention generally relates sub-lithographic semiconductor structures, and in particular, conductors which may be used as electrical fuses and methods of making the same.
2. Description of Related Art
In the semiconductor industry, fuses are used in integrated circuits (ICs) for improving manufacturing yield or customizing generic integrated circuits. A fuse can be disconnected (known as “blowing a fuse”) (1) by passing an electric current so that electromigration takes place which either causes an open in the fuse element or increases the resistance, or (2) by applying a laser to melt the fuse. A fuse blown by electric current is referred to as an electrical fuse (e-fuse). After blowing the fuse, it is considered programmed.
E-fuses can have one of two orientations, horizontal or vertical. When viewed from top down, a horizontal e-fuse typically includes a line having two wide pad areas at either end with a thinner link in between and connecting the pad areas of the line. The wide pads are to make connections which provide current. The entire fuse including the link is parallel to the substrate, thus a horizontal fuse. A horizontal fuse is typically made of polysilicon and a silicide and found on and in direct contact with the substrate, thus in the front end of line (FEOL) of an IC. A horizontal orientation of the fuse consumes valuable real estate on the chip. Furthermore, as ICs fabrication moves to replacement metal gate processes or FinFET configurations, fabrication of e-fuses in the FEOL becomes difficult to integrate.
Therefore, a reliable fuse that minimizes real estate and is compatible with replacement metal gate and finFET integration is needed.